1 files changed, 60 insertions, 0 deletions

diff --git a/xdelta3/go/src/xdelta/rstream.go b/xdelta3/go/src/xdelta/rstream.go
new file mode 100644
index 0000000..3e7265f
--- /dev/null
+++ b/xdelta3/go/src/xdelta/rstream.go
@@ -0,0 +1,60 @@
+package xdelta
+
+
+import (
+        "io"
+        "math/rand"
+)
+
+const (
+        blocksize = 16380
+)
+
+func WriteRstreams(t *TestGroup, seed, offset, len int64,
+        first, second io.WriteCloser) {
+        go writeOne(t, seed, 0, len, first)
+        go writeOne(t, seed, offset, len, second)
+}
+
+func writeOne(t *TestGroup, seed, offset, len int64, stream io.WriteCloser) error {
+        t.WaitGroup.Add(1)
+        if offset != 0 {
+                // Fill with other random data until the offset
+                if err := writeRand(rand.New(rand.NewSource(^seed)), offset, stream); err != nil {
+                        return err
+                }
+        }
+        if err := writeRand(rand.New(rand.NewSource(seed)),
+                len - offset, stream); err != nil {
+                return err
+        }
+        t.WaitGroup.Done()
+        return stream.Close()
+}
+
+func writeRand(r *rand.Rand, len int64, s io.Writer) error {
+        blk := make([]byte, blocksize)
+        for len > 0 {
+                fillRand(r, blk)
+                c := blocksize
+                if len < blocksize {
+                        c = int(len)
+                }
+                if _, err := s.Write(blk[0:c]); err != nil {
+                        return err
+                }
+                len -= int64(c)
+        }
+        return nil
+}
+
+func fillRand(r *rand.Rand, blk []byte) {
+        for p := 0; p < blocksize; {
+                v := r.Int63()
+                for i := 7; i != 0; i-- {
+                        blk[p] = byte(v)
+                        p++
+                        v >>= 8
+                }
+        }
+}